Agents and factors that regulate the formation, accumulation and activity of cyclic AMP and cyclic GMP in tissues will be examined. Agents tested will include a variety of drugs, hormones and autacoids. Concentrations of these cyclic nucleotides in urine, plasma and other extracellular fluids will be examined in patients with various clinical disorders for the purpose of developing new diagnostic tests and examining the pathophysiology of some disorders. BIBLIOGRAPHIC REFERENCES: Mittal, C.K. and F. Murad: Formation of cyclic AMP by guanylate cyclase preparations after activation with sodium azide. Clin. Res. 25, 49a, 1977. Ichihara, K., J. Larner, H. Kimura and F. Murad: Activation of liver guanylate cyclase by bile salts and contaminants in crude secretin and pancreozymin preparations. Clin. Res. 25, 32a, 1977.